A standard mixing valve is known from commonly owned patent application Ser. No. 08/962,373 (now U.S. Pat. No. 5,896,601) of Humpert and from European patent document 0,309,443 of Dagiantis (US equivalent U.S. Pat. No. 4,960,154) which has a housing holding a fixed valve plate having a flat outer surface generally centered on and perpendicular to an axis and formed offset from the axis with a pair of angularly offset and axially throughgoing inlet ports and offset therefrom with a pair of axially throughgoing outlet ports. Hot and cold water is supplied under pressure to the inlet ports and passages in the housing connect the outlet ports to respective users, e.g. a faucet and a sprayer. A movable valve plate in the housing has an inner surface flatly engaging the outer surface of the fixed valve plate and an opposite outer surface and is formed with an axially throughgoing inlet port alignable with the fixed-plate inlet ports and offset from the respective inlet port with an axially throughgoing outlet port alignable with the fixed-plate outlet ports. A cover element fixed in the housing to the outer surface of the movable plate forms a fluid-flow passage at the outer surface between the movable-plate inlet port and the movable-plate outlet port. An actuator can shift the cover element and movable plate between a closed position with one of the movable-plate ports out of alignment with the respective fixed-plate ports and blocked by the fixed-plate outer face and two open positions in each of which the movable-plate inlet port is aligned with at least one of the fixed-plate inlet ports and the movable-plate outlet port is aligned with a respective one of the fixed-plate outlet ports.
Thus with this system the movable plate is shifted in one direction to direct the output to one of the outputs and in the opposite direction to direct the output to the other of the outputs. In addition as is standard the movable plate can be shifted from side to side or pivoted so that, when separate hot- and cold-water inlets are provided, the temperature of the outputted water can be varied also.
In order to prevent inadvertent displacement of the actuator into one of its positions, for example to prevent unintended pressurization of the sprayer, the actuator of above-cited EP 0,309,443 is a handle provided with a pivotal lever that is urged by a spring into a normal position engaging a rim of a fixed part of the valve housing and preventing pivoting in one direction. When this lever is operated its end moves away from the rim and rides against an outside surface of the valve housing where it is visible and can scratch its surface. Such a system is simple but unattractive. Its operation is apparent to the user and it can in the long run damage the valve housing.